Interplanetary - Nuclear Thermal Propulsion

From MIT News: "Fueling research in nuclear thermal propulsion". From the article:

    There are three broad types of rocket propulsion: chemical, where thrust is achieved by the combustion of rocket propellants; electrical, where electric fields accelerate charged particles to high velocities to achieve thrust; and nuclear, where nuclear energy delivers needed propulsion.

    Nuclear propulsion, which is only used in space, not to get to space, further falls into one of two categories: nuclear electric propulsion uses nuclear energy to generate electricity and accelerate the propellant. Nuclear thermal propulsion, which is what Hampson is researching, heats a propellant using nuclear power. A significant advantage of NTP is that it can deliver double the efficiency (or more) of the chemical equivalent for the same thrust. A disadvantage: cost and regulatory hurdles. “Sure, you can get double the efficiency or more from a nuclear propulsion engine, but there hasn’t been a mission case that has needed it enough to justify the higher cost,” Hampson says.

    Until now.

    With a human mission to Mars becoming a very real possibility — NASA plans on sending astronauts to Mars as early as the 2030s — NTP might soon come under the spotlight.     

More:

•  "US to build nuclear reactor on moon by 2030: NASA"--New York Post. This article from 1/13/2026 relates:

     NASA and the US Department of Energy are working to develop and deploy a nuclear reactor on the moon’s surface within the next four years — fulfilling one of President Trump’s visions for space development, according to authorities.

    The agencies signed a memorandum of understanding anticipating they will accomplish the ambitious goal of deploying nuclear reactors both on the moon and in orbit by the year 2030, the DOE and NASA announced on Tuesday.

    The reactors will use a fission surface power system, capable of producing “safe” and “plentiful electrical power,” for future long lunar missions — regardless of sunlight or temperature, the department said. 

•  "We’re building nuclear spaceships again—this time for real"--Ars Technica (2024). This article gives a history of U.S. research and tests into building nuclear powered rockets, why the concept was abandoned in the 1970s, and why interest is waxing again:

    DARPA’s website says it has always held to a singular mission of making investments in breakthrough technologies for national security. What does a nuclear-powered spaceship have to do with national security? The military’s perspective was hinted at by General James Dickinson, a US Space Command officer, in his testimony before Congress in April 2021.

    He said that “Beijing is seeking space superiority through space attack systems” and mentioned intelligence gathered on the Shijian-17, a Chinese satellite fitted with a robotic arm that could be used for “grappling other satellites.” That may sound like a ridiculous stretch, but it was enough get a go-ahead for a nuclear spaceship.

    And the apparent concern regarding hypothetical threats has continued. The purpose of the Demonstration Rocket for Agile Cislunar Operations (DRACO) project, stated in its environmental assessment, was to “provide space-based assets to deter strategic attacks by adversaries.” Dickinson’s worries about China were quoted in there as well.

    “Let’s say you have a time-critical mission where you need to quickly go from A to B in cislunar space or you need to keep an eye on another country that is doing something near or around the Moon, and you need to move in very fast. With a platform like DRACO, you can do that,” said DARPA’s Dodson.

    Two years after DARPA stepped in, the preliminary design phase was completed, and Lockheed won a half-billion-dollar contract to build DRACO. But DARPA wasn’t the only one paying. NASA chipped in as well. The two agencies made DRACO a joint project and split the bill 50-50.

•  "After more than 60 years of development, here is the nuclear engine that is set to go to Mars with NASA."--Farmingdale Observer (2025).

    For decades, NASA has been working on an engine that is faster and more efficient than traditional chemical propulsion. One of the most serious avenues is nuclear thermal propulsion (NTP). How does this work? Heat a gas, usually hydrogen, in a nuclear reactor, then expel it at high speed to generate a much more powerful thrust. With this system, Mars could be reached in just 45 days. General Atomics, a key player in nuclear research, has just announced a major breakthrough in this technology. Scott Forney, President of GA-EMS, is delighted with the latest tests: We are very encouraged by these positive results proving that the fuel can survive these operating conditions, bringing us closer to the realisation of safe and reliable nuclear thermal propulsion for cislunar and deep space missions.

    The DRACO programme, piloted by NASA and DARPA, plans to demonstrate an NTP engine as early as 2027. But the challenges remain: ultra-resistant materials, heat management in space and, above all, astronaut safety in the face of an on-board nuclear reactor. Meanwhile, SpaceX continues to make progress on the chemical propulsion front with its Starship rocket, designed for interplanetary missions. Elon Musk still has a head start on reusable launchers, but if nuclear propulsion becomes viable, he could well find himself facing unexpected competition. What’s more, with the rise of China, which is aiming for a manned mission to Mars by 2033, the duel with the United States looks set to be fierce. And this time, it’s hard to predict who will get there first.